The hafnium oxide material class is characterized by the coexistence of several polymorphs between which phase transitions are induced by means of composition and external electric fields. Pyroelectric materials, which convert heat into electrical energy, exhibit the largest response at such morphotropic or field-induced phase transitions. The hafnium oxide material system is of special interest for pyroelectric applications since it allows for scalable and semiconductor-compatible fabrication. Here, we report large pyroelectric coefficients at the morphotropic transition from the ferroelectric orthorhombic to the centrosymmetric tetragonal phase. The electric field-induced transition between these two phases in doped HfO₂ is found to yield large pyroelectric coefficients of up to −142 µCm⁻² K⁻¹, a value that is 20 times larger compared to AlN.

中文翻译：

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铁电氧化ha薄膜在形变和场致相变处的热释电响应增强

氧化铪材料类别的特征在于多种多晶型物的共存，在这些多晶型物之间通过成分和外部电场引起相变。将热量转化为电能的热释电材料在这种同向相变或场致相变时表现出最大的响应。氧化铪材料系统对热电应用特别感兴趣，因为它允许可扩展和半导体兼容的制造。在这里，我们报告了从铁电正交相到中心对称四方相的同向转变处的大热电系数。发现掺杂 HfO _{2 中}这两相之间的电场诱导转变产生高达 -142 µ 的大热电系数Cm ^-2  K ^-1，该值比AlN大20倍。